Chair back



FIG. 1 is a front perspective view of the chair back.

FIG. 2 is a back perspective view of the chair back.

FIG. 3 is a right elevation view of the chair back.

FIG. 4 is a left elevation view of the chair back.

FIG. 5 is a front elevation view of the chair back.

FIG. 6 is a back elevation view of the chair back; and,

FIG. 7 is a top plan view of the chair back.

The broken lines shown in the drawing are for illustrative purposes only and form no part of the claimed design. 

The ornamental design for the chair back, as shown and described. 